The present invention is directed to a hand-held power tool with a torque-limiting unit.
Hand-held power tools, such as cordless screwdrivers, cordless drills or cordless impact drills have a high amount of drive torque. Limiting this torque is desirable for many applications. Adjustable torque limitation makes it possible, e.g., to screw a number of screws into a work piece with the same level of screw-down torque; a torque-limiting unit disengages as soon as the screws apply a certain level of torque resistance to the motor output shaft. The operator can adjust the torque-limiting unit according to the maximum torque required for the task at hand.
Publication DE 103 09 057 A1 makes known a hand-held power tool with adjustable torque limitation with which an operator adjusts—using an actuating means—the maximum torque to be transferred from a motor output shaft to a tool driver. If the torque produced by the motor exceeds a maximum torque level that was set, an overload clutch disengages and the connection between the motor output shaft and the tool driver is separated. The actuating means, which are capable of being grasped by an operator, are retained by a retaining element in the position set by the operator, the retaining element including a notched ring with radially outwardly directed notches and an external plate spring. The plate spring engages from the radially outward direction into the notches of the retaining element and retains it in the desired position.